The pneumatic tire may have raised temperatures accompanied by, among others, promotion of temporal variations such as changes in property of materials, or causation to a break or such in a high-speed running, which is unfavorable from a viewpoint of durability. In particular, for a truck bus radial (TBR) tire or off-road radial (ORR) tire to be heavy-loaded in use, or for a run flat tire in a flat run (running with an internal pressure of 0 kPa), the reduction of tire temperature has been a significant desideratum for enhancement of durability. For example, a run flat tire has reinforcing rubber crescents, which become very hot with concentrated radial deformations in a flat run, giving a significant influence on durability.
In a known relevant art for a promoted heat dissipation of pneumatic tire, a flat pneumatic tire provided with a rim guard has many ridges disposed on the rim guard to provide an increased surface area for promotion of heat dissipation.
In the above-noted art for a promoted heat dissipation of pneumatic tire, the tire has an increased surface area for promotion of heat dissipation, while additional enhancement in efficiency of heat dissipation is desirable.